1. Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display device and a method for driving the same.
2. Discussion of the Related Art
Each of Pixels constituting an OLED display device includes an OLED constituted by an anode, a cathode, and an organic light emitting layer interposed between the anode and the cathode, and a pixel circuit for independently driving the OLED. The pixel circuit mainly includes a switching thin film transistor (TFT), a capacitor, and a driving TFT. The switching TFT charges a data voltage in the capacitor in response to a scan pulse. The driving TFT controls an amount of current supplied to the OLED in accordance with the data voltage charged in the capacitor, to adjust an emission intensity of the OLED.
In such an OLED display device, however, pixels thereof exhibit characteristic differences in terms of, for example, the threshold voltage (Vth) and mobility of driving TFTs, due to process deviation, etc. Voltage drop of a high-level voltage VDD may also occur. As a result, the amount of current to drive each OLED may vary and, as such, luminance deviation may be exhibited among the pixels. Generally, characteristic differences initially exhibited among driving TFTs may cause display of spots or patterns on a screen. On the other hand, characteristic differences exhibited among driving TFTs in accordance with operation of the driving TFTs to drive OLEDs may cause a reduction in the lifespan of an OLED display panel or generation of after images.